Stent, method for processing stent, and method of stenting a patient

ABSTRACT

The subject invention pertains instruments for use in nuclear spin tomography comprising a metal alloy comprising aluminum, vanadium, and titanium. In a specific embodiment, the subject invention relates to cardiovascular stents which can exhibit a low incidence of artifacts and are viewable in a nuclear spin tomography unit. The subject invention also pertains to a method for processing instruments for use in nuclear spin tomography. Spin processing can comprise application of a wet chemical etching solution. In a specific embodiment, the wet chemical etching solution can comprise three parts hydrochloric acid and two parts saltpeter acid.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. patent applicationSer. No. 10/851,931, filed May 21, 2004, which is a divisionalapplication of U.S. patent application Ser. No. 10/091,988, filed Mar.5, 2002, now U.S. Pat. No. 6,780,338, which claims the benefit of GermanApplication Serial No. 20104145.6, filed Mar. 9, 2001, all of which arehereby incorporated by reference herein in their entirety, including anyfigures, tables, or drawings.

DESCRIPTION

This invention relates to the use of a material in claim 1 and a processin claims 3 and 5. In today's stent technology it is desirable to usecardiovascular stents that are able to adequately prop open the vessel,that can be accurately positioned and that, and this is new—can beviewed with nuclear spin tomography. Traditional stents are made ofstainless steel and show distinct image distortions, so calledartifacts. These artifacts occur when materials with high magneticsusceptibility are used.

A goal of the invention is to show means by which the occurrence ofartifacts in combination with the stents and nuclear spin tomography canbe avoided.

The solution is recapitulated in claims 1 through 5.

An alloy of 3 percent aluminum by weight and 2.5 percent vanadium byweight, with the remainder being titanium, known as material TIA13V2.5or material No. 3.7194 or 253.7195 (ASTM Grade 9), shows especially fewimage artifacts and has sufficient hardness to be suitable forinterventional instruments used in nuclear spin tomography.

The above named alloy according to ASTM Grade 9 is harder than an alloyaccording to ASTM Grade 5 or ISO 3.765 or 3.7165. This would have thefollowing components: 90% titanium, 6% aluminum, and 4% vanadium. Thematerial is more flexible than the so-called ASTM grade 9 material andis therefore more suitable for expanding a stent with the help of aballoon catheter.

Materials that are made to be artifact free but created with toolscontaining magnetizing components after processing show an increase inscreen artifacts which rubbed off the tools. A reduction of surfacemagnetism can be achieved through dipping in etching solutions whichetches the materials the tools are made of. The rub-off from the toolsis eliminated by the wet chemical etching solution. Such an etchingsolution that removes the iron impurities consists for example of 3parts hydrochloric acid and 2 parts saltpeter acid and can be furtherreduced with additional parts water in the etching process.

Stents manufactured in the manner here described can be ideally observedin nuclear spin tomography units in magnetic flux density >1.0 Testa. Itwas possible, for example with an unexpanded stent having a diameter of1 mm, that was balloon expanded to a diameter of 4 mm, to clearly seeall the stent struts, the so-called strats. It was also possible to geta good look inside the expanded stent. So-called in-stent-restenose inthe interior of the stent can be seen when a stent has been treated inthis manner.

1-5. (canceled)
 6. A method for control of in-stent-restenosis,comprising: positioning a stent in a vessel, wherein the stent comprisesTIA13V2.5; and viewing in-stent-restenosis within an inner lumen of thestent with nuclear spin tomography, wherein the TIA13V2.5 exhibits a lowincidence of artifacts in nuclear spin tomography, wherein viewingin-stent-restenosis within the inner lumen of the stent with nuclearspin tomography is useful for control of in-stent-restenosis.
 7. Themethod according to claim 6, wherein the stent consists essentiallyentirely of TIA13V2.5.
 8. The method according to claim 6, whereinTIA13V2.5 has the following composition by weight: up to 0.08% C; up to0.03% N₂; up to 0.15% O₂; 2.0% to 3.0% V; 2.5% to 3.5% Al; up to 0.25%Fe; up to 0.015% H₂; and the balance Ti.
 9. The method according toclaim 7, wherein TIA13V2.5 has the following composition by weight: upto 0.08% C; up to 0.03% N₂; up to 0.15% O₂; 2.0% to 3.0% V; 2.5% to 3.5%Al; up to 0.25% Fe; up to 0.015% H₂; and the balance Ti.
 10. A methodfor control of in-stent-restenosis, comprising: positioning a stent in avessel, wherein the stent comprises TIA16V4; and viewingin-stent-restenosis within an inner lumen of the stent with nuclear spintomography, wherein the TIA16V4 exhibits a low incidence of artifacts innuclear spin tomography, wherein viewing in-stent-restenosis within theinner lumen of the stent with nuclear spin tomography is useful forcontrol of in-stent-restenosis.
 11. The method according to claim 10,wherein the stent is expandable with a balloon catheter.
 12. The methodaccording to claim 10, wherein the stent consists essentially entirelyof TIA16V4.
 13. The method according to claim 10, wherein the TIA16V4has the following composition by weight: up to 0.08% C; up to 0.05% N₂;up to 0.2% O₂; 3.5% to 4.5% V; 5.5% to 6.75% Al; up to 0.4% Fe; up to0.015% H₂; and the balance Ti.
 14. The method according to claim 12,wherein the TIA16V4 has the following composition by weight: up to 0.08%C; up to 0.05% N₂; up to 0.2% O₂; 3.5% to 4.5% V; 5.5% to 6.75% Al; upto 0.4% Fe; up to 0.015% H₂; and the balance Ti.
 15. A method ofstenting a patient, comprising: stenting a patient with a stent, whereinthe stent comprises: TIA13V2.5, wherein the TIA13V2.5 exhibits a lowincidence of artifacts in nuclear spin tomography.
 16. The methodaccording to claim 15, wherein the stent consists essentially entirelyof TIA13V2.5.
 17. The method according to claim 15, wherein TIA13V2.5has the following composition by weight: up to 0.08% C; up to 0.03% N₂;up to 0.15% O₂; 2.0% to 3.0% V; 2.5% to 3.5% Al; up to 0.25% Fe; lessthan 0.015% H₂; and the balance Ti.
 18. The method according to claim16, wherein TIA13V2.5 has the following composition by weight: up to0.08% C; up to 0.03% N₂; up to 0.15% O₂; 2.0% to 3.0% V; 2.5% to 3.5%Al; up to 0.25% Fe; up to 0.015% H₂; and the balance Ti.
 19. A method ofstenting a patient, comprising: stenting a patient with a stent, whereinthe stent comprises TIA16V4, wherein the TIA16V4 exhibits a lowincidence of artifacts in nuclear spin tomography.
 20. The methodaccording to claim 19, wherein the stent is expandable with a ballooncatheter.
 21. The method according to claim 19, wherein the stentconsists essentially entirely of TIA16V4.
 22. The method according toclaim 19, wherein the TIA16V4 has the following composition by weight:up to 0.08% C; up to 0.05% N₂; up to 0.2% O₂; 3.5% to 4.5% V; 5.5% to6.75% Al; up to 0.4% Fe; up to 0.015% H₂; and the balance Ti.
 23. Themethod according to claim 21, wherein the TIA16V4 has the followingcomposition by weight: up to 0.08% C; up to 0.05% N₂; up to 0.2% O₂;3.5% to 4.5% V; 5.5% to 6.75% Al; up to 0.4% Fe; up to 0.015% H₂; andthe balance Ti.
 24. A method of stenting a patient, comprising: stentinga patient with a stent processed with tools containing magnetizingcomponents, wherein prior to stenting the patient exposing the surfaceof the stent processed with tools containing magnetizing components toan etching solution that etches the magnetizing components, whereinexposing the surface of the stent processed with tools containingmagnetizing components reduces surface magnetism of the stent, whereinreducing surface magnetism of the stent reduces the occurrence ofartifacts from the stent in nuclear spin tomography.
 25. The methodaccording to claim 24, wherein the etching solution etches ironimpurities.
 26. The method according to claim 25, wherein the etchingsolution comprises: 3 parts hydrochloric acid; and 2 parts saltpeteracid.
 27. The method according to claim 26, wherein the etching solutionfurther comprises water.